The conventional water-soluble coolant used in machine tools becomes contaminated during use, which contamination involves not only solid contaminants such as machine chips and the like, but also contamination by typical oils such as hydraulic fluids, such oils being referred to as "tramp oil".
At present, various cleaning processes and apparatus have been proposed for removing various contaminants, the most simple and easiest contaminant to remove being the course solid contaminants such as machining chips. Most attempts to recycle coolant, however, have been unable to effectively remove a majority of both solid and liquid contaminants, namely both solid fines (ie, the very small or fine solid particles) and the tramp oil. While numerous attempts have been made to recycle coolant, most recycling attempts have, at best, attempted to remove only part of the contaminants, such as either solids or liquids.
One prior attempt to remove both the solid fines and the portable apparatus illustrated in my earlier U.S. Pat. No. 4,872,997, issued Oct. 10, 1989 and entitled "Coolant Recycling System and Method". The arrangement of this earlier patent employs a tank into which the contaminated coolant is deposited, with the supply of coolant to the tank passing through a filter in an attempt to remove the solid finds. The coolant in the tank is then bubbled by injecting air streams into the bottom thereof, which creates upwardly-passing bubble streams in an attempt to effect separation of the tramp oil so that it can rise to the surface. While the arrangement of the aforesaid patent has been partially effective in recycling coolant, nevertheless this prior arrangement has been less than optimum in terms of performance. More specifically, it has been observed that the bubbling technique is slow in terms of effecting separation of the tramp oil, and hence the technique thus does not possess the speed which is desired for practical commercial application in most use environments. Further, this bubbling technique is not believed to be as suitable for use in a portable recycling device which is either transported from plant to plant, or moved about from machine to machine within a single manufacturing plant, due to the criticality of the air pressure which must be used to perform the bubbling process.
Accordingly, it is an object of this invention to provide an improved recycling apparatus which can effectively remove both solid fines and tramp oil, and which can do so at a rate which is believed to be commercially satisfactory so as to permit its efficient and economical use, with the apparatus being particularly suitable for incorporation into a portable arrangement so as to be movable from machine to machine.
In the improved coolant recycling apparatus of the present invention, there is provided first and second storage tanks mounted on a small wheeled cart so that the overall apparatus is portable and can be readily moved about. The first tank has a suction device associated therewith to which is coupled a flexible suction hose terminating in a wand. This is used to suck the contaminated coolant from the sump of the machine tool, whereby the coolant flows through the suction device and thence through a filter associated therewith for removing the larger solids, whereupon the contaminated coolant is then deposited or collected in the first tank. A pump sucks the contaminated coolant from the first tank and supplies it to a filter disposed adjacent the upper end of the second tank. This filter has a stack of oil absorbent pads therein which effectively remove the tramp oil as the coolant flows downwardly through the filter and then collects in the bottom of the second tank. The clean coolant in the bottom of the second tank is sent back to the pump through suitable valving which, by suitable control, enables the coolant to be sucked out of the second tank and then supplied to a discharge hose which can be utilized to supply the clean coolant back into the sump of a machine tool. The apparatus also has a small storage tank for containing concentrated new coolant (which also normally contains a biocide) so that concentrated new coolant can be added to the cleaned coolant which has been collected in the second tank for supply to the machine tool sump.
With the arrangement as described above, the tramp oil can be effectively removed and the oil absorbent pads can be readily replaced when necessary, and at the same time the coolant can be recycled and cleaned of contaminants in an efficient and time saving manner. This arrangement also permits the coolant to be withdrawn from the machine tool, recycled and cleaned, and then resupplied to the same machine tool if desired within a short period of time so that coolant recycling can hence be carried out in an efficient and time saving manner.
Other objects and purposes of the invention will be apparent to persons familiar with arrangements of this general type upon reading the following specifications and inspecting the accompanying drawings.